1. Field of the Invention
The invention relates to a method and system for programming an extended path for an autonomous mobile unit and to a computer program product and a computer-readable storage medium with a computer program stored thereon for programming an extended path for an autonomous mobile unit.
2. Description of Related Art
Repetitive activities are increasingly being reassigned to service robots. Examples of such activities include cleaning, transporting, distributing seed over relevant areas, and lawn mowing.
The problem with the service robots, to which associated surface-processing devices are attached, is that the surface-processing device is expected to cover as much of the available space as possible with as few paths as possible being traversed more than once. Moreover, the effort needed to program this path must be sufficiently low to require little computing capacity. This is the only way to ensure acceptable time characteristics during the programming process.
There is the added problem in the case of a cleaning robot whose function is to perform cleaning tasks in a supermarket, for instance, that additional obstacles in the form of customers with trolleys appear when the robot is being used while the supermarket is open for business. If the dimensions of the work area and the position of the obstacles located therein are known, it is possible with the aid of a pre-programming method to program an optimum path the traversing of which takes minimum time while simultaneously taking into consideration as much of the surface to be traversed as possible. The service robot starts traversing the path when the pre-programmed path has been pre-programmed and determined.
A pre-programming method of this type is known, for example, from DE 198 04 195 A1. However, any obstacles that may briefly appear, for example customers with their trolleys, consequently cannot be taken into consideration when the path is being pre-programmed. In this case the service robot detects the obstacles while moving. The robot takes evasive action, which is to say it departs from the pre-programmed path, bypasses the obstacle, and returns after the evasive action to its original path. A type of programming and execution of such evasive action is also known from DE 198 04 195 A1. However, the section of the original path that was not traversed owing to the evasive action remains unprocessed or uncleaned at this time and will have to be processed or cleaned subsequently.
Two different post-programming methods are known for subsequently processing unprocessed path sections of this type. In the case of the first post-programming method, the previously executed pre-programming method is executed a second time. The already traversed and accordingly processed sub-section of the original path is no longer taken into consideration here, while the unprocessed, omitted sub-section is taken into consideration during subsequent programming.
The disadvantage of this method, however, is that a completely new path is determined for the remaining section of the original path still to be processed on account of taking the omitted sub-section into consideration. Yet this complete re-programming results in unnecessarily long programming times and places a high demand on computing power. A provision in this case of the second known post-programming method is for the unprocessed path section to be appended at the end of the original path and to be traversed on completion of the path. However, this method results in unnecessarily extended paths and so is also inefficient.
Other path programming methods are known from “Approximation Algorithms for Lawn Mowing and Milling”, Arkin E. M. et al., Angewandte Mathematik und Informatik (Applied Mathematics and Computer Science), University of Cologne, Report No. 97.255, 1997.